While loops in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple while loop

What is the output of this MATLAB code?

MATLAB

i = 1;
while i <= 3
    disp(i)
    i = i + 1;
end

A

2
3
4

B

1
2
3
4

C

1
2
3

D

1
2

💡 Hint

The loop runs while i is less than or equal to 3, increasing i by 1 each time.

The loop starts with i=1 and prints i. It increments i by 1 each time until i becomes 4, which stops the loop. So it prints 1, 2, and 3.

❓ Predict Output

intermediate

Sum calculation using while loop

What is the value of variable sum after running this code?

MATLAB

sum = 0;
i = 1;
while i <= 5
    sum = sum + i;
    i = i + 1;
end

A 15

B 10

C 5

D 0

💡 Hint

The loop adds numbers from 1 to 5 to sum.

The loop adds 1 + 2 + 3 + 4 + 5 = 15 to sum.

🔧 Debug

advanced

Identify the error in this while loop

What error does this MATLAB code produce when run?

MATLAB

i = 1;
while i < 5
    disp(i)
    % missing increment of i
end

A Syntax error: missing end statement

B Infinite loop (program never stops)

C Runtime error: variable i undefined

D Outputs numbers 1 to 4 then stops

💡 Hint

Check if the loop variable changes inside the loop.

Since i is never increased, the condition i < 5 is always true, causing an infinite loop.

❓ Predict Output

advanced

While loop with break statement

What is the output of this MATLAB code?

MATLAB

i = 1;
while true
    disp(i)
    if i == 3
        break
    end
    i = i + 1;
end

A

1
2
3

B

1
2

C

1
2
3
4

D Infinite loop with no output

💡 Hint

The loop stops when i equals 3.

The loop prints i starting from 1. When i reaches 3, the break stops the loop, so output is 1, 2, 3.

🧠 Conceptual

expert

Number of iterations in nested while loops

How many times will the inner disp statement run in this MATLAB code?

MATLAB

i = 1;
count = 0;
while i <= 3
    j = 1;
    while j <= 2
        disp([i, j])
        count = count + 1;
        j = j + 1;
    end
    i = i + 1;
end

A 2

B 5

C 3

D 6

💡 Hint

Multiply the number of outer loop runs by inner loop runs.

Outer loop runs 3 times, inner loop runs 2 times each, so total is 3*2=6.